Covering Panel

ABSTRACT

The invention relates to a cladding panel ( 10 ) with two pairs of side edges ( 10   a - 10   d ) lying opposite one another, whereby at least one pair of side edges is provided with coupling means ( 12 ) embodied essentially in the form of a groove ( 12   a,    12   c ) and a tongue ( 12   b,    12   d ) and extending along the respective side edge. According to the invention, at least one section ( 14   a 1) of the boundary surface of the groove ( 12   a,    12   c ) or/and at least one section ( 14   b 1) of the boundary surface of the tongue ( 12   b,    12   d ) is provided with a roughening ( 18 ).

The invention relates to a cladding panel with two pairs of side edgeslying opposite one another, whereby at least one pair of side edges isprovided with coupling means embodied essentially in the form of agroove and a tongue and extending along the respective side edge.

Cladding panels of this type are generally known. Reference is made byway of example to EP 1 036 244 B1.

The generic panels are usually produced by essentially cuboid-shaped rawpanels, i.e., raw panels the side surfaces of which assigned to the sideedges run essentially orthogonally to the walking surface, beingmachined, e.g., by milling to form the coupling means on at least onepair of side edges, namely in the form of a groove in the area of theone side surface and of a tongue in the area of the other side surface.The purpose of this chip removal is thereby always to achieve thesmoothest surfaces possible in order to be able to slide two panels thatare connected to one another via groove and tongue relative to oneanother in the longitudinal direction of the respective side edge whenlaying the cladding panels.

One problem that generic cladding panels always have to deal with inpractice are the seasonal variations in the relative humidity. In timesof high relative humidity the cladding panels expand because ofswelling, whereas they shrink during the heating period in winterbecause of the low relative humidity. This swelling and shrinking causesthe formation of cracks between panels abutting on one another even if,as is customary with many types of cladding panels currently availableon the market, the coupling means of the cladding panels are embodiedwith integrated locking means, which extend in the longitudinaldirection of the respective side edge of the cladding panel and try tocounteract a relative movement of the two panels in a direction runningin the panel plane and orthogonally to the respective side edge. Furthercauses for the formation of cracks to be mentioned are the effects ofstatic and mechanical-dynamic stresses, as exerted on the floor, e.g.,by heavy pieces of furniture or by walking on it. With rectangularcladding panels this crack formation problem occurs in particular at theshort sides of the panels. Furthermore, the crack formation problemoccurs to a particular extent if the panels, as is customary today, arelaid in a freely floating manner on the subfloor, i.e., are notconnected to the subfloor by separate connecting means and are not gluedto one another.

To prevent crack formation, EP 0 843 763 A1, EP 1 024 234 A1 and EP 1026 341 A1 suggested a cladding panel with which, in the connected stateof two panels, the lower lip delimiting the groove of the one panelpresses against the tongue of the respective other panel with aprestressing force. This prestressing force is thereby produced by apermanent displacement of the lower lip from its rest position, whichthe lip assumes in the unconnected state of the two panels. Thispermanent displacement causes a constant mechanical stress and a gradualfatigue of the panel material.

The object of the present invention is therefore to provide a claddingpanel of the type mentioned at the outset, with which the formation ofcracks between two panels connected to one another can be counteracted,without providing a prestressing force of this type.

This object is attained according to the invention by a cladding panelof the type mentioned at the outset, with which at least one section ofthe boundary surface of the groove or/and at least one section of theboundary surface of the tongue is provided with a roughening.

In connection with the present invention, “boundary surface” herebyrefers to the surface extending from the side surface of the respectiveside edge, following the groove with a face normal facing into thegroove or following the tongue with a face normal facing away from thetongue and ending on the other side of the groove or of the tongue oncemore at the side surface of the side edge.

Providing the roughening according to the invention means that thefriction between the groove of the one panel and the tongue of the otherpanel is increased, so that a relative displacement of the twointerconnected panels in the longitudinal direction of the groove ortongue is made more difficult. The crack formation on the panel siderunning orthogonally to this longitudinal direction is thus counteractedas well. This means that if the cladding panel is a rectangular claddingpanel with a short side and a long side, the crack formation can becounteracted at the short side of the panel in that, at least on thelong side, at least one section of the boundary surface of groove or/andtongue is provided with a roughening. Naturally, providing a rougheningin the area of the groove or/and the tongue of the short side of thepanel also results in a reduction of the tendency to crack formation onthe long side of the panel.

With respect to achieving a highest possible friction it is preferred ifthe at least one section of the boundary surface provided with theroughening extends both over essentially the entire length of therespective side edge and in the circumferential direction of theboundary surface over essentially the entire circumference of theboundary surface. However, it can also be desirable, not least forreasons of manufacturing engineering, for the at least one section ofthe boundary surface provided with the roughening to extend merely overa part of the length of the respective side edge or/and in thecircumferential direction merely over a part of the boundary surface.

The friction between the boundary surface of the groove and thecorresponding boundary surface of the tongue can be further increased inthat, whenever both at least one section of the boundary surface of thegroove and at least one section of the boundary surface of the tongueare provided with a roughening, these roughenings are provided at leastin part on sections of the boundary surfaces of groove and tonguecomplementary to one another. Two sections of the boundary surfaces ofgroove or tongue of one and the same panel are to be considered“complementary” within the meaning of this claim if the groove sectionprovided with a roughening of the one panel and the tongue sectionprovided with a roughening of the other panel bear against one anotherin the connected state of these two panels when two identical panels areconnected.

The roughening can be embodied in different ways:

For example, at least one section provided with a roughening can beformed by a toothing. In order to achieve a highest possible frictionbetween two panels connected to one another, it is thereby suggestedthat the tooth sequence direction of the toothing runs essentially inthe longitudinal direction of the respective side edge, whereas thetooth extension direction runs essentially in the circumferentialdirection of the groove or the tongue. “Tooth sequence direction”thereby means the direction in which the teeth of-the toothing followone another; with a conventional gear wheel thus the circumferentialdirection of the gear wheel. By contrast, the “tooth extensiondirection” thereby means the direction in which the individual toothextends; with a conventional gear wheel with straight teeth thus theaxial direction.

The toothing can be formed, e.g., by an essentially chipless machining,for instance by indenting, serrating or the like. But additionally oralternatively it is also possible to form the toothing by a chip-formingmachining, e.g., by piercing, milling or the like. With bothalternatives for producing the toothing it is, however, advantageous touse a tool the rotational speed of which is adjusted to the feed rate ofthe panel such that its circumferential speed essentially corresponds tothe feed rate of the panel.

In a second embodiment variant, which can be used additionally oralternatively to the formation of the roughened section as a toothing,at least one section provided with a roughening can be formed by aplurality of wood fibers protruding from the surface of the respectivesection of the boundary surface. In order to cause the fibers to standup, the surface can be treated with an agent, e.g., with awater-dilutable varnish (such as an unplasticized aqueous copolymerlatex) which releases the fibers at least in part from their materialcompound, e.g., solid wood, MDF or another wood material, raises andfixes them.

According to a third embodiment variant, which can again be usedadditionally or alternatively to the two embodiment variants explainedabove, at least one section provided with a roughening can be formed bya plurality of particles applied to the surface of the respectivesection of the boundary surface. These particles can be, e.g., particlesof micronized polypropylene wax with a size of between approximately 30μm and 75 μm. Furthermore, these particles can be joined to the surfaceof the respective section of the boundary surface by means of anadhesion promoter, e.g., a water-dilutable varnish (such as anunplasticized aqueous copolymer latex).

As already indicated above, at least a core of the panel can be formedof a wood material, e.g., solid wood, a chipboard, an MDF board or thelike. But basically it is also possible to apply the principlesaccording to the invention to other materials, e.g., compact laminate,plastic or the like.

As already mentioned above as well, the coupling means can be embodiedwith integrated locking means extending in the longitudinal direction ofthe respective side edge. These locking means can thereby be formed fromthe core material, e.g., in one piece. But it is basically alsoconceivable to embody the locking means or/and the coupling means in orat a coupling unit connected to the core of the panel. This couplingunit can be connected to the core of the panel in that, e.g., a suitablematerial, e.g., plastic, a wood extrudate or the like is injected into aprepared indentation in the side surface of the panel and issubsequently machined in a material-removing manner to form the couplingmeans or/and the locking means. But as an alternative it is alsopossible to insert a prefabricated part with coupling means or/andlocking means prefabricated thereon into the prepared indentation.

The invention can be used in a particularly advantageous manner if thecladding panel is a flooring panel, and particularly if the flooringpanel is designated to be laid in a floating manner or/and without theuse of adhesive to connect adjacent panels.

The invention is explained in more detail below by means of exemplaryembodiments on the basis of the enclosed drawings. They show:

FIG. 1 A top view of a cladding panel according to the invention;

FIG. 2 A partial top view of a covering layer formed by a plurality ofcladding panels of this type;

FIG. 3 A perspective view of the end of the groove and the end of thetongue of a cladding panel provided with a roughening according to theinvention;

FIG. 4 A diagrammatic side view of the panel according to FIG. 3 toexplain the method of embodying the roughening; and

FIGS. 5 and 6 Views similar to FIGS. 3 and 4 of a further embodiment ofa cladding panel according to the invention.

In FIG. 1, a panel according to the invention is designated in generalas 10. The panel 10 is embodied as a rectangular panel and has two longsides 10 a and 10 b and two short sides 10 c and 10 d arrangedrespectively in pairs opposite one another. In the exemplary embodimentshown, the panel 10 is provided with coupling means both on the longsides 10 a and 10 b and on the short sides 10 c and 10 d, which couplingmeans serve to connect the panel 10 to adjacent panels 10′, 10″, . . .in the longitudinal direction L or in the transverse direction Q (seeFIG. 2).

The coupling means 12 are composed essentially in the form of a groove12 a provided on the long side 10 a and a tongue 12 b provided on thelong side 10 b, which together form the coupling means of the long side,and a groove 12 c provided on the short side 10 c and a tongue 12 dprovided on the short side 10 d, which together form the coupling meansof the short side. These coupling means 12 can be embodied in differentvariants, some of which will be explained below in more detail withreference to FIGS. 3 through 6. But all of these coupling means have thecommon property that pairs 12 a/ 12 b, 12 c/12 d of grooves and tonguesassigned to one another are embodied such that in the connected state oftwo identical panels 10 the pairs interlock in the manner of jigsawpuzzle pieces, thus without prestressing, i.e., in particular withoutthe lower groove boundary lip being permanently deflected out of itsrest position.

On the one hand, the representation according to FIG. 3 can beinterpreted as showing the groove edge 10 a or 10 c in the bottom leftin a first perspective view, and in the top right in a secondperspective view the tongue edge 10 b or 10 d of one and the same panel10. But since the panels joined to form a covering layer are embodied tobe identical, the representation can, on the other hand, also beinterpreted as showing the edges 10 b, 10 a′ or 10 c, 10 d″ adjoiningone another of two panels 10, 10′ or 10, 10″ embodied to be identicaladjoining one another (see FIG. 2).

The embodiment represented in FIG. 3 is a groove/tongue profile whichcan be connected by angling into one another two adjacent panels 10 and10′ or 10″. To this end, the left groove panel 10 in FIG. 3 can lie flaton the floor, whereas the right tongue panel 10′ or 10″ in FIG. 3 issupplied from the side in a position angled with respect to thehorizontal, until its tongue 12 b, 12 d engages with the groove 12 a, 12c of the panel 10. Subsequently, the locking means 14 provided at thecoupling means 12 a, 12 c or 12 b, 12 d of the two panels 10 and 10′ or10″ can be brought into engagement with one another by pivoting downwardthe tongue panel 10′, 10″. In the exemplary embodiment shown, thelocking means 14 are thereby formed on the groove side 12 a, 12 c of thepanels by a recess 14 a embodied in the upper surface of the lower lip16 delimiting the groove 12 a, 12 c. On the tongue side of the panel 10,the locking means 14 are formed by a projection 14 b provided on theunderside of the tongue 12 b, 12 d.

In the connected state of two panels 10, the engagement of the couplingmeans 12 prevents a relative movement of the two panels 10 in the upwarddirection H (see FIG. 1), i.e., in a direction running orthogonally tothe panel plane or walking surface E of the panels 10, whereas theinteraction of the locking means 14 prevents a relative movement of thetwo panels 10 in a direction running in the panel plane E andorthogonally to the respective side edge 12 a through 12 d. The panelplane E is thereby spanned by the longitudinal direction L (direction ofthe long sides 10 a and 10 b) and the transverse direction Q (directionof the short sides 10 c and 10 d) of the panels 10.

In contrast to the panels of the prior art, the panels 10 according tothe invention additionally have a roughening 18 which at least impedes arelative movement of two panels 10 connected to one another in thelongitudinal direction of the respective side edge 10 a/10 b, 10 c/10 d.To this end, at least one surface section of the surfaces bearingagainst one another of the coupling means 12 and the locking means 14are provided with a roughening 18 of this type. In the exemplaryembodiment represented in FIG. 3, this is on the one hand the base area14 a 1 of the recess 14 a on the groove panel shown on the left in FIG.3, and the top area 14 b 1 of the projection 14 b of the tongue panelshown on the right in FIG. 3. Please note that the two surfaces 14 a 1and 14 b 1 mentioned above bear against one another in the connectedstate of two adjacent panels, and that their respective roughenings thusinteract with one another, which effectively increases the friction inthe longitudinal direction of the respective side edges 10 a/10 b, 10c/10 d. Within the meaning of the present application, the surfaces 14 a1 and 14 b 1 of the panel 10 thus form “complementary” surfaces.

In the longitudinal direction of the two side edges, the roughenings 18extend preferably over the entire length of the edges, whereas they areprovided merely on a part of the boundary surfaces of the groove or thetongue in the circumferential direction U, as shown in FIG. 3. Thelatter, however, is mainly due to reasons of production technology.

As indicated diagrammatically in FIG. 3, the roughenings 18 arerespectively formed by a toothing, the teeth 18 a of which follow oneanother in the longitudinal direction of the respective side edge 10a/10 b, 10 c/10 d (“tooth sequence direction”), whereby each individualtooth extends essentially in the circumferential direction U, i.e.,orthogonally to the longitudinal direction of the respective side edge(“tooth extension direction”).

As shown diagrammatically in FIG. 4, the toothing 18 can be embodied,e.g., by pressing the teeth 18 a into the base area 14 a 1 of the recess14 a or into the top area 14 b 1 of the projection 14 b. To this end, arotating tool 20 or 22 is brought into engagement with the surfaces 14 a1 or 14 b 1, the circumferential surface 20 a or 22 a of which tool hasa counter-toothing corresponding to the toothing 18 to be embodied.Attention must further be paid to the fact that the tool 20 or 22rotates synchronously to the movement of the panel 10, i.e., such that,with a rotation about the axis 20 b or 22 b, its circumferential speedcorresponds to the feed rate of the panel 10 in the direction of therespective side edge 10 a through 10 d.

In addition, FIG. 4 shows another tool 24 which corresponds to the tools20 and 22 in terms of structure and function, but is arranged such thatit provides a toothing to an oblique boundary surface 14 a 2 of therecess 14 a. Note must further be taken of the fact that no analogoustoothing tool is provided for the oblique surface 14 b 2 at the tonguepanel shown on the right in FIG. 4. However, even the one-sidedprovision of a toothing can further increase the friction between thetwo panels.

FIGS. 5 and 6 show a modified embodiment that corresponds essentially tothe embodiment according to FIGS. 3 and 4. In FIGS. 5 and 6, analogousparts are thus provided with the same reference numbers as in FIGS. 3and 4, but increased by the number 100. Furthermore, FIGS. 5 and 6 willbe described below only as far as they differ from the embodimentexplained previously, to the description of which explicit reference ishereby made otherwise.

One the one hand, the panel 110 represented in FIGS. 5 and 6 differsfrom the panel 10 according to FIGS. 3 and 4 in that the coupling means112 embodied at the side edges 110 a-110 d are not embodied such thattwo adjacent panels can be connected to one another by angling thetongue panel into the groove panel, but that the panels 110 areconnected by being moved towards one another in an essentially planarmanner parallel to the panel plane E. In this case, the locking means114 are formed by a projection 114 a at the free end of the lower lip116 delimiting the groove 112 a, 112 c and by a recess 114 b in the areaof transition of the tongue 112 b, 112 d into the panel 110. When thetongue 112 b, 112 d is inserted into the groove 112 a, 112 c, the lowerlip 116 is thus deflected, i.e., bent downward, until the nose 114 a cancatch in the recess 114 b. As a result of this catching, the lower lip116 returns again to its rest position shown in FIG. 5, in which it isfree of any mechanical deformation.

Also in the exemplary embodiment shown in FIGS. 5 and 6, both the groove112 a, 112 c and the tongue 112 b, 112 d are provided with a roughening118, namely on the one hand at an upper boundary surface 116 a of thelower lip 116 and on the other hand at the lower boundary surface 122 ofthe tongue 112 b, 112 d. In the present case, the roughenings 118 areformed by particles 118 a, which can be applied by means of a sprayingtool 128 or 130 (see FIG. 6) to the surfaces 116 a and 126, preferablyusing an adhesion promoter which, after having dried, keeps theparticles 118 a on the surfaces 116 a, 126.

It should further be stated that it is basically also conceivable toprovide merely one of the two complementary surfaces 116 a, 126 withsprayed-on particles of this type, in order to achieve a higher frictionbetween the two panels 110. Furthermore, it is conceivable to applyparticles of this type also to the surfaces not visible in FIG. 5 on thelower side of the upper groove boundary lip 132 and on the upper side ofthe tongue 112 b, 112 d. Another embodiment variant for the rougheningprovided according to the invention is to be explained as well below onthe basis of the diagrammatical representations according to FIGS. 5 and6:

Also a solvent can be applied to the surfaces 116 a and 126 by means ofthe spraying tools 128 and 130, which solvent starts to dissolve a woodmaterial, e.g., solid wood, MDF or the like used to form the panels 110,at least so much that individual wood fibers disengage at least in partfrom the material compound and project out of the surface when thetreatment agent has dried. In this case, 118 a designates the woodfibers projecting from the surfaces 116 a and 126 a in FIG. 5.

The following has to be added:

The panels 10, 110 can be made of any material, e.g., a wood materialsuch as, e.g., solid-wood boards, MDF boards, chipboards or the like,but also of compact laminate, plastic and suitable panel materials ofthis type.

If the panels are to be used as flooring panels, they can have a core 10e, 110 e, as indicated in FIGS. 4 and 6 respectively with the panel 10,110 shown in the bottom left, which core is embodied, e.g., as an MDFboard (medium-density fiberboard), whereby a decorative layer 10 f, 110f is glued to this core 10 e, 110 e on its walking surface E, and aleveling layer 10 g, 110 g is glued to its underside B resting on thefloor, opposite the walking side E. The decorative layer 10 f, 110 f cancomprise, e.g., one or more plies of printed paper, which is or aresaturated with synthetic resin. In an analogous manner, the levelinglayer 10 g, 100 g can be formed by a laminate layer comprising severalpaper plies of this type.

The groove 112 a, 112 c or the tongue 112 b, 112 d do not necessarilyhave to be formed directly of the material of the core 110 e. Rather, asindicated by a dashed line in FIG. 6, it is also possible to inject asuitable material, e.g., plastic, a wood extrudate or the like into arecess 150 prepared in the side surface 110 a through 110 d, and let itcure there, and to embody the groove 112 a, 112 c or the tongue 112 b,112 d subsequently by machining.

1. Cladding panel (10) with two pairs of side edges (10 a-10 d) lying opposite one another, whereby at least one pair of side edges is provided with coupling means (12) embodied essentially in the form of a groove (12 a, 12 c) and a tongue (12 b, 12 d) and extending along the respective side edge, whereby at least one section (14 a 1) of the boundary surface of the groove (12 a, 12 c) and at least one section (14 b 1) of the boundary surface of the tongue (12 b, 12 d) is provided with a roughening (18) in the form of a toothing (18), which roughenings are provided on sections complementary to one another of the boundary surfaces of groove and tongue, whereby the tooth sequence direction of the toothing (18) runs essentially in the longitudinal direction (L or Q) of the respective side edge (10 a-10 d), whereas the tooth extension direction runs essentially in the circumferential direction (U) of the groove (12 a, 12 c) or of the tongue (12 b, 12 d), and whereby the complementary sections (14 a 1, 14 b 1) bear against one another and are in engagement with one another in the connected state of the panel with another identical panel.
 2. Cladding panel according to claim 1, characterized in that the toothing (18) is formed by an essentially chipless machining, for instance by indenting, serrating or the like.
 3. Cladding panel according to claim 1 or 2, characterized in that the toothing (18) is formed by a chip-forming machining, e.g., by piercing, milling or the like.
 4. Cladding panel (110) with two pairs of side edges (110 a-110 d) lying opposite one another, whereby at least one pair of side edges is provided with coupling means (112) embodied essentially in the form of a groove (112 a, 112 c) and a tongue (112 b, 112 d) and extending along the respective side edge, whereby at least one section (116 a) of the boundary surface of the groove (112 a, 112 c) or/and at least one section (126) of the boundary surface of the tongue (112 b, 112 d) is provided with a roughening (118) in the form of a plurality of wood fibers (118 a) released at least in part from the material compound of the cladding panel and protruding from the surface of the respective section of the boundary surface.
 5. Cladding panel according to one of claims 1 through 4, characterized in that, with a rectangular cladding panel with a short side (10 c, 10 d) and a long side (10 a, 10 b), at least one section (14 a 1, 14 b 1) of the boundary surface of groove or/and tongue is provided with a roughening (18) at least on the long side (10 a, 10 b).
 6. Cladding panel according to one of claims 1 through 5, characterized in that the at least one section (14 a 1, 14 b 1) of the boundary surface provided with the roughening (18) extends over merely a part of the length of the respective side edge.
 7. Cladding panel according to one of claims 1 through 5, characterized in that the at least one section (14 a 1, 14 b 1) of the boundary surface provided with the roughening (18) extends over essentially the entire length of the respective side edge.
 8. Cladding panel according to one of claims 1 through 7, characterized in that the at least one section (14 a 1, 14 b 1) of the boundary surface provided with the roughening (18) extends over merely a part of the circumference of the boundary surface in the circumferential direction (U) of the boundary surface.
 9. Cladding panel according to one of claims 1 through 7, characterized in that the at least one section (14 a 1, 14 b 1) of the boundary surface provided with the roughening (18) extends over essentially the entire circumference of the boundary surface in the circumferential direction (U) of the boundary surface.
 10. Cladding panel according to one of claims 1 through 9, characterized in that at least a core (10 e) of the panel (10) is manufactured from a wood material, e.g., solid wood, a chipboard, an MDF board or the like, or/and from compact laminate or/and from plastic.
 11. Cladding panel according to one of claims 1 through 10, characterized in that the coupling means (12) are embodied with integrated locking means (14) extending in the longitudinal direction (L or Q) of the respective side edge (10 a-10 d).
 12. Cladding panel according to claim 11, characterized in that the locking means (14) are manufactured in one piece from the material of the core (10 e).
 13. Cladding panel according to one of claims 1 through 12, characterized in that the coupling means (112) or/and the locking means (114) are embodied in or at a coupling unit (150) connected to the core (110 e) of the panel (110).
 14. Cladding panel according to one of claims 1 through 13, characterized in that it is a flooring panel. 